Core and slot liner

ABSTRACT

A core for a dynamoelectric machine has a pair of generally opposite end faces, and wall means is provided in the core for defining at least one winding receiving slot intersecting the opposite end faces, respectively. At least a pair of layers of generally thin dielectric material are associated in overlaying relation and disposed in the slot. A set of apertures are arranged in a preselected pattern in the layers and disposed in non-aligning relation, and a set of non-apertured sections in the layers are arranged in the layer between the apertures, respectively. At least some of the apertures in each layer are communicated with at least some of the non-aperture sections in an adjacent layer, and the at least some apertures in one of the layers is also communicated with the wall means of the at least one slot. 
     A method of assembling a core, a method of treating a core, and a method of assembling a slot liner are also disclosed.

CROSS-REFERENCE TO RELATED PATENTS

This application is a division of the now copending commonly assignedparent application Ser. No. 173,929 filed June 6, 1988 which is adivision of grandparent application Ser. No. 66,840 filed June 26, 1987and; is related to U.S. Pat. No. 4,485,126 issued Nov. 27, 1984 toJoseph R. Gaietto et al. and U.S. Pat. No. 4,559,698 issued Dec. 24,1985 to Eugene C. Bair et al., and each of these parent and grandparentapplications and related patents is incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates in general to electrical apparatus and inparticular to a core for a dynamoelectric machine and a slot liner.

BACKGROUND OF THE INVENTION

In the past various different methods were employed to treat a core of adynamoelectric machine with a hardenable liquid adhesive material inorder to bond together the interfacing lamination surfaces of the core.A typical past core had a lamination stack, and the laminations may havebeen retained in interfacing relation in the stack by suitable means,such as welding, bonding or cleating or the like for instance. Windingmeans associated with the stator included a plurality of coils havingopposite side turn portions received in slots provided therefor in thecore, and the coils also had opposite end turn portions arranged ingenerally annular groupings thereof adjacent the opposite end faces ofthe core. Of course, suitable insulation, such as for instance a slotliner of dielectric material, was provided in the core slots toelectrically insulate the opposite side turn portions of the coils fromthe core, and suitable winding retaining means, such as slot wedges orthe like for instance, were positioned in the slots of the core tomaintain the opposite side turn portions of the coils againstdisplacement from the slots into the bore of the core.

In one of the aforementioned past treatment methods for the core whenthe laminations were retained by welding or cleating, the core and itswinding means were baked or preheated to a preselected temperature, andwhile at such an elevated temperature, the core and its winding meanswere immersed or dipped into a bath of the liquid adhesive material.When the core was so immersed, it is believed that the liquid adhesivematerial entered into the core for the most part from the outercircumferential portion of the core and penetrated by capillary actionbetween the interfacing lamination surfaces of the core. When laterremoved from the liquid adhesive material bath, the core and its windingmeans were rebaked or reheated to effect the hardening or curing of theliquid adhesive material which had adhered to the core. In someinstances, the core and its winding means may have been reimmersed inthe liquid adhesive material bath and rebaked. While the above discussedpast treatment method may have bonded together the laminations of thecore to provide adequate core strength, one of the disadvantageous orundesirable features of such past treatment method is believed to bethat it may have been necessary to wipe excess liquid adhesive materialfrom the opposite end faces and the circumferential surface of the coreprior to baking the core to cure the liquid adhesive material.

Still another past method of treating a loose wound core involved abolt-down bonding process as shown in U.S. Pat. No. 3,821,846 issuedJuly 2, 1974 to Bernard J. Pleiss, Jr. In this past method, a pluralityof bolts were extended through bolt holes provided in the looselamination stack of the loose wound core so as to mount an opposite endface of the loose wound core against a bolt down fixture. Upon torquingof the bolts, the interfacing lamination surfaces in the looselamination stack were forced or clamped together by the bolts generallyin the vicinity of the bolt holes thereby to establish generally axialcompression regions generally adjacent the bolt holes between theopposite end faces of the loose wound core. When so mounted to thebolt-down fixture, the loose wound core was preheated and immersed intoa liquid adhesive material bath with the exception of the annular endturn grouping of the windings adjacent the winding lead ends. Since thebore of the loose wound core was mounted on an alignment mandrel, it isbelieved for the most part that the liquid adhesive material may havepenetrated by capillary action from the outer circumferential surface ofthe loose wound core between the interfacing lamination surfaces thereofexcept for the axial compression regions established adjacent the boltholes. Albeit not discussed or even suggested in the Pleiss, Jr. patent,it is believed that the possibility may have existed wherein some of theliquid adhesive material may have been transferred in some manner fromthe slots of the loose wound core by capillary action between theinterfacing lamination surfaces of the loose wound core. Thereafter, theloose wound core was baked to effect the curing of the liquid adhesivematerial in the loose wound core thereby to bond it together.Nevertheless, it is believed that this past treatment method for loosewound cores has at least generally the same disadvantageous orundesirable features of the previously discussed past treatment method.

As disclosed in U.S. Pat. No. 4,559,698 issued Dec. 24, 1985 to EugeneC. Bair et al., liquid adhesive material was applied or metered ontoannular end turn groupings of winding means of a core, and in responseto a preselected rotation sequence of the core, the liquid adhesivematerial was flowed from the end turn groupings along opposite side turnportions of the winding means into slots of the core within insulatingslot liners and slot wedges in the core slots. Since the slot liners andslot wedges in part overlaid each other within the core slots, theliquid adhesive material was flowed between the overlaying parts of theslot liners and slot wedges into communication with interfacinglamination surfaces in the core intersecting with the core slots. Bycapillary action, the liquid adhesive material penetrated into the corebetween the interfacing lamination surfaces, and in response tosubsequent baking of the core, the liquid adhesive material was curedthereby to bond the core and its winding means into a unitary mass.While this past treatment method undoubtedly exhibited many salientfeatures, it is believed that when the necessary amount of liquidadhesive material was applied to insure proper distribution of theliquid adhesive material between the interfacing lamination surfaces toeffect adequate core bond strength, some of the liquid adhesive materialmay have flowed from some of the core slots onto the opposite end facesof the core. Of course, prior to baking of the core, it was necessary towipe away any liquid adhesive material which may have accumulated on theopposite end faces of the core, and as previously mentioned, it isbelieved that the additional operation of removing the liquid adhesivematerial from the opposite end faces of the core may have been adisadvantageous or undesirable feature of this past treatment method.

In West German Patent No. 2,826,260, liquid adhesive material was flowedthrough a plurality of apertures in a slot liner in each core slot so asto adhere the slot liner in the slot. The West German Patent allegesthat the adherence of the slot liners in the slots obviates displacementof the slot liners and windings contained therein in response tovibration which may occur when the windings are energized and also thatsuch apertures facilitate cooling of the windings. However, one of thedisadvantageous or undesirable features of this past treatment method isbelieved to be that the voltage creepage distance through the aperturesin the slot liners between the windings within the slot liners and thecore slots would not meet requirements of at least some nationalregulatory agencies, such as for instance NEMA or UnderwritersLaboratories, Inc. in the U.S.A. and Canadian Standards Association inCanada.

SUMMARY OF THE INVENTION

Among the several objects of the present invention may be noted theprovision of an improved core for a dynamoelectric machine and animproved slot liner for a winding receiving slot in a core of adynamoelectric machine which overcome the above discusseddisadvantageous or undesirable features, as well as others, of the priorart; the provision of such improved core and slot liner in which atleast a pair of layers of dielectric material are arranged at least inpart in overlaying relation with a plurality of apertures in each layerbeing predeterminately misaligned with the apertures in an adjacentlayer so that at least some of the apertures in each layer communicatewith respective non-apertured sections of the adjacent layer; theprovision of such improved core and slot liner wherein a marginal wallof each aperture in each layer is predeterminately spaced from themarginal walls of adjacent apertures in the adjacent layer; theprovision of such improved core in which one of the layers of the slotliner is disposed at least adjacent wall means in the core defining atleast one winding receiving slot between a pair of opposite end faces ofthe core and another of the layers of the slot liner is disposed atleast adjacent a part of the winding means for the core received in theat least one slot in the core; the provision of such improved core andslot liner in which the one layer of the slot liner is located between apair of opposite cuffs on the another layer of the slot liner so thatwhen the slot liner is assembled with the core, the cuffs are disposedat least adjacent the opposite end faces of the core generally at theintersections of the at least one slot with the opposite end faces ofthe core; the provision of such improved core and slot liner in whichthe components utilized therein are simplistic in design, easilyassembled and economically manufactured. These as well as other objectsand advantageous features of the present invention will be in partapparent and in part pointed out hereinafter.

In general and in one form of the invention, a core for a dynamoelectricmachine has a pair of generally opposite end faces, and wall means inthe core for defining at least one winding receiving slot intersectswith the opposite end faces, respectively. At least a pair of layers ofgenerally thin dielectric material are associated at least in part inoverlaying relation and disposed at least in part with the at least oneslot. The layers include a set of apertures arranged in a preselectedpattern and disposed in non-aligning relation and also a set ofnon-apertured sections between the apertures. At least some of theapertures in each layer are communicated with at least some of thenon-apertured sections in an adjacent layer, and the at least someapertures in one of the layers are also communicated with the wallmeans, respectively.

Further in general, a slot liner in one form of the invention isprovided for use in a winding receiving slot in a core for adynamoelectric machine. The slot liner has a plurality of layers ofgenerally thin dielectric material associated at least in part inoverlaying relation. Each layer includes a plurality of aperturesextending therethrough and arranged in a preselected pattern. Theapertures in adjacent layers are disposed in non-aligning relation, andat least some of the apertures in each layer communicate with anon-apertured section in another of the layers, respectively.

Also in general, a method is provided in one form of the invention forassembling a slot liner for a dynaomelectric machine. The slot linerincludes at least a pair of sheets of generally thin dielectric materialwith each sheet having a plurality of apertures extending therethroughin a preselected pattern and a plurality of non-apertured sectionsbetween the apertures, respectively. In practicing this method, thesheets are associated at least in part in overlaying relation. Theapertures in adjacent sheets are disposed in non-aligning relation witheach other, and at least some of the apertures in each sheet arecommunicated with at least some of the non-apertured sections in theadjacent sheets, respectively, when the sheets are asociated in theiroverlaying relation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing a sheet of generally thin dielectricmaterial having a plurality of apertures extending through the sheet ina preselected pattern;

FIG. 2 is a plan view showing another sheet of generally thin dielectricmaterial having another plurality of apertures extending through theanother sheet in another preselected pattern;

FIG. 3 is a plan view illustrating in part a slot liner in one form ofthe invention and showing the sheets of FIGS. 1 and 2 arranged inoverlaying relation with the apertures in the sheet of FIG. 2 beingshown as circular dotted lines and illustrating principles which may bepracticed in a method of assembling a slot liner for a dynamoelectricmachine;

FIG. 4 is an enlarged partial sectional view taken along line 4--4 inFIG. 3;

FIG. 5 is an enlarged interrupted left end elevational view of theoverlaid sheets in FIG. 3 showing a pair of opposite imperforate stripson one of the sheets formed into a pair of opposite cuffs;

FIG. 6 is a partial perspective exploded view of a core in one form ofthe invention and illustrating principles which may be utilized in amethod of assembling the core;

FIG. 7 is a sectional view taken along line 7--7 in FIG. 6;

FIG. 8 is generally the same as FIG. 7 but additionally showing windingmeans associated with the core;

FIG. 9 is an enlarged sectional view taken along line 9--9 in FIG. 8;

FIG. 10 is a schematic sectional view of the core of FIG. 6 illustratingthe insertion of one coil of the winding means into slots providedtherefor in the core;

FIG. 11 is a perspective view of a core mounted to a rotatable mandrelat an operation station for dispensing a hardenable liquid adhesivematerial onto the winding means and illustrating principles which may bepracticed in a method of treating a core;

FIG. 12 is an enlarged sectional view taken along line 12--12 of FIG. 9with the winding means removed for clarity and illustrating the flow ofthe hardenable liquid adhesive material through the slot liner so as towet by capillary action interfacing lamination surfaces in a laminationstack of the core;

FIG. 13 is a plan view showing a sheet of generally thin dielectricmaterial having a plurality of apertures extending therethrough in apreselected pattern with the sheet being utilized in an alternative slotliner in one form of the invention and an alternative method ofassembling a slot liner, respectively;

FIG. 14 is an enlarged end view showing the sheet of FIG. 13 folded uponitself;

FIG. 15 is a perspective view of the alternative slot liner formed fromthe sheet of FIG. 13;

FIG. 16 is a sectional view showing the alternative slot liner of FIG.15 in its assembled position in a slot of the lamination stack of FIG.6;

FIG. 17 is an enlarged sectional view taken along line 17--17 in FIG.16;

FIG. 18 is an enlarged sectional view taken along line 18--18 in FIG. 17and illustrating the flow of hardenable liquid adhesive material throughthe alternative slot liner to wet by capillary action the interfacinglamination surfaces of the stack;

FIG. 19 is a plan view showing a sheet of generally thin dielectricmaterial having a plurality of apertures extending therethrough in apreselected pattern with the sheet being utilized in another alternativeslot liner in one form of the invention and another alternative methodof assembling a slot liner, respectively;

FIG. 20 is an enlarged end view showing the sheet of FIG. 19 folded uponitself;

FIG. 21 is a perspective view of the alternative slot liner formed fromthe sheet of FIG. 19;

FIG. 22 is a sectional view showing the alternative slot liner of FIG.21 in its assembled position in a slot of the lamination stack of FIG.6;

FIG. 23 is an enlarged sectional view taken along line 23--23 in FIG.22; and

FIG. 24 is an enlarged sectional view taken along line 24--24 in FIG. 23and illustrating the flow of hardenable liquid adhesive material throughthe alternative slot liner to wet by capillary action the interfacinglamination surfaces of the stack.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

The exemplifications set out herein illustrate the preferred embodimentsof the invention in one form thereof, and such exemplifications are notto be construed as limiting in any manner either the scope of theinvention or the scope of the disclosure thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference now to the drawings in general, there is illustrated amethod of assembling a slot liner or slot liner assembly 31 for use in awinding receiving slot 33 in a core or stator 35 of a dynamoelectricmachine (not shown) (FIG. 6). Slot liner 31 includes at least a pair ofsheets or layers 37,39 of generally thin dielectric material, and thesheets have a plurality of apertures or openings 41,43 extendingtherethrough in a preselected pattern, respectively (FIGS. 1 and 2).Sheets 37,39 also have a plurality of non-apertured sections or portions45,47 interconnecting between apertures 41,43, respectively (FIGS. 1 and2). In the practice of this method, sheets 37,39 are associated at leastin part in overlaying relation (FIG. 3). Apertures 41,43 in adjacentsheets 37,39 are disposed or associated in non-aligning relation witheach other, and at least some of the apertures in each sheet arecommunicated with at least some of the non-apertured sections 45,47 inthe adjacent sheets, respectively, when the sheets are associated intheir overlaying relation (FIGS. 3 and 4).

More particularly and with specific reference to FIGS. 1-4, thedielectric material of sheets 37,39 may be a Mylar sheet materialavailable from E. I. duPont de Nemours and Company, Wilmington, Del.;however, it is contemplated that the sheets may be formed of variousdifferent types of dielectric material within the scope of the inventionso as to meet at least some of the objects thereof. Sheets 37,39 eachinclude a pair of generally opposite surfaces 49,49a and 51,51a.Opposite surfaces 49,49a of sheet 37 are interconnected by a pair ofsets of generally opposite marginal edges 53,53a and 55,55a, andadjacent ones of the opposite marginal edges intersect with each other.Opposite surfaces 51,51a of sheet 39 are interconnected by another pairof sets of generally opposite marginal edges 57,57a and 59,59a, andadjacent ones of the opposite marginal edges 57,57a and 59,59a intersectwith each other. As further discussed hereinafter, sheet 39 is providedwith a pair of generally opposite imperforate parts or strips 61,61aextending along opposite marginal edges 59,59a and between oppositesurfaces 51,51a of the sheet, and if desired, such imperforate stripsmay be delineated by fold lines 63,63a impressed in the sheet in spacedapart relation from opposite marginal edges 59,59a. While sheets 37,39are illustrated herein as having a particular configuration for purposesof disclosure, it is contemplated that other sheets having differentconfigurations may be utilized within the scope of the invention so asto meet at least some of the objects thereof.

Apertures 41,43 in sheets 37,39 have wall means, such as marginal wallsor sidewalls 65,67 or the like for instance, defining the particularconfigurations of the apertures, as best seen in FIG. 4, and a pair ofopposite ends or end portions of wall means 65 intersect with oppositesurfaces 49,49a of sheet 37 while another pair of opposite ends or endportions of wall means 67 intersect with opposite surfaces 51,51a ofsheet 39, respectively. Although the particular configurations ofapertures 41,43 are illustrated herein for purposes of disclosure, it iscontemplated that other apertures having various differentconfigurations, such as generally rectangular openings or slits or thelike for instance, may be utilized in the sheets within the scope of theinvention so as to meet at least some of the objects thereof.Furthermore, while apertures 41,43 are shown spaced or arranged insheets 37,39 in the aforementioned preselected patterns, as illustratedin FIGS. 1 and 2 for purposes of disclosure, it is contemplated that theapertures may be arranged in various different patterns in the sheetswithin the scope of the invention so as to meet at least some of theobjects thereof.

When sheets 37,39 are associated in their overlaying relation, aspreviously mentioned and as best seen in FIGS. 3-5, opposite surface 49aof sheet 37 is engaged with opposite surface 51 of sheet 39, andopposite marginal edges 55,55a of sheet 37 are aligned generally alongopposite imperforate strips 61,61a of sheet 39 in spaced apart relationwith opposite marginal edges 59,59a of sheet 39 while the other oppositemarginal edges 53,53a and 57,57a on sheets 37,39 are located at leastgenerally adjacent each other, respectively. Thus, since apertures 41,43are arranged in preselected patterns in sheets 37,39, as previouslymentioned, it may be noted that wall means 65,67 of apertures 41,43 insheets 37,39 are disposed in non-aligning or staggered relation witheach other when the sheets are associated in their aforementionedoverlaying relation, respectively. Furthermore, it may also be notedthat non-apertured sections 45,47 in sheets 37,39 are engaged generallyabout the intersections of the opposite ends of aperture wall means65,67 with opposite surfaces 49a,51 on sheets 37,39 when the sheets areassociated in their aforementioned overlaying relation, respectively.

While apertures 41,43 communicate with non-apertured sections 45,47 inadjacent sheets 37,39 when the sheets are associated in theiraforementioned overlaying relation, it may be noted that a preselectedspace or distance S of at least generally about three thirty-seconds ofan inch or 0.094 inches (2.39 mm) is established or provided for voltagecreepage purposes, as discussed in greater detail hereinafter, betweenwall means 65 of each aperture 41 in sheet 37 and the wall means 67 ofapertures 43 in sheet 39 which are spaced adjacent respective ones ofsuch each aperture 41 in sheet 37. Likewise, the same space S is alsoestablished between wall means 67 of each aperture 43 in sheet 39 andthe wall means 65 of apertures 41 in sheet 37 which are spaced adjacentrespective ones of such each aperture 43 in sheet 39.

Upon the establishment of the preselected space S between apertures41,43 in adjacent sheets 37,39 in the manner discussed above, oppositeimperforate strips 61,61a of sheet 39 may be deformed or folded overgenerally along fold lines 63,63a so as to form a pair of generallyopposite cuffs 69,69a which extend generally angularly with respect tosheet 39, as best seen in FIG. 5. Upon the formation of opposite cuffs69,69a on sheet 39, it may be noted that the opposite cuffs arepositioned at least in part in spaced overlaying relation with sheet 37adjacent its opposite marginal edges 55,55a, respectively. It may benoted that upon the formation of opposite cuffs 69,69a on sheet 39, thecuffs engage sheet 37 along its opposite marginal edges 55,55a servingto retain or capture sheet 37 in its aforementioned overlaying relationwith sheet 39 thereby to maintain the preselected space S betweenapertures 41,43 in the adjacent sheets, respectively. Even if sheets37,39 shift relative to each other generally lengthwise or alongopposite cuffs 69,69a on sheet 39, it may be noted that the preselectedpattern in which apertures 41,43 are arranged obviate the possibility ofwall means 65,67 of the apertures being spaced apart from each other adistance less than the preselected space S.

When cuffs 69,69a are formed on sheet 39, as discussed above, sheets37,39 in their overlaying relation may be deformed or shaped into apreselected configuration at least generally approximating theconfiguration of slot 33 in core 35, as shown in FIG. 6. When so shaped,sheets 37,39 are deformed into a generally U-shaped or horseshoe shapedconfiguration, and aligned adjacent opposite marginal edges 53,57 and53a,57a of the sheets are arranged or positioned generally in laterallyspaced apart relation with respect to each other. With the deformedsheets 37,39 in their generally U-shaped configuration, it may be notedthat the sheets are provided with opposite sides or side portions 71,73and 75,77, and generally arcuate ends or end portions 79,81 on thesheets are integrally interconnected between the opposite side portions,respectively. Of course, opposite side portions 75,77 and end portion 81on sheet 39 extend between opposite cuffs 69,69a on sheet 39, andopposite side portions 71,73 and end portion 79 on sheet 37 are arrangedin overlaying relation with opposite side portions 75,77 and end portion81 between the opposite cuffs on sheet 39, respectively. Albeit notshown for the purpose of drawing simplification and brevity ofdisclosure, it is contemplated that the above discussed assembling andshaping of slot liner 31 may be accomplished by suitable apparatus, andit is also contemplated that such apparatus may also be employed toeffect the placement or injection of the slot liners in core slots 33therefor in the manner discussed in detail hereinafter. If a moredetailed discussion is desired concerning the construction and operationof typical apparatus which is representative of the type mentionedabove, reference may be had to U.S. Pat. No. 3,514,836 issued June 2,1970 to L. M. Mason. To complete the description relating to slot liner31 and the method of assembling it, it is contemplated that thepreselected pattern of apertures 41,43 in sheets 37,39 may provide agreater number of such apertures in overlaying end portions 79,81 of theslot liner than in either of the overlaying opposite side portions 71,73and 75,77 of the slot liner, or vice versa.

With reference to FIGS. 6 and 7, core 35 in one form of the inventionhas a lamination stack 83 with a pair of generally opposite end faces85,85a, and the laminae in the stack is formed of generally thinferromagnetic material. A yoke or yoke section 87 extends generallyaxially between opposite end faces 85,85a of stack 83 so as to define acircumferential surface 89 about the stack, and a plurality of teeth 91extend generally radially inwardly on preselected pitch axes A from theyoke section and generally in axial row formations between the oppositeend faces, respectively. Each tooth 91 in stack 83 has a tip end 93defining in part a bore 95 which extends generally axially through stack83 between opposite end faces 85,85a. A plurality of wall means in stack83 defines slots 33 with each slot including a pair of opposed sidewalls97,99 on adjacent ones of teeth 91 and a generally arcuate end wall 101on yoke 87 interconnecting between the opposed sidewalls, respectively.Opposed sidewalls 97,99 and end wall 101 of each slot 33 extendgenerally axially through stack 83 intersecting with opposite end faces85,85a, and a plurality of openings or slot entrances 103 are providedbetween adjacent ones of tooth tips 93 interconnecting the slots andbore 95 with the openings and extending generally axially between theopposite end faces so as to intersect therewith, respectively. Whileslots 33 are shown herein as round-bottom slots, it is contenplated thatother slots having various other configurations, such as for instance aflat-bottom slot or the like, may be utilized within the scope of theinvention so as to meet at least some of the objects thereof. Tocomplete the description of stack 83, a plurality of interfacinglamination surfaces 105 in the stack intersect with circumferentialsurface 89, opposed sidewalls 97,99 and end walls 101 of each slot 33,and tooth tips 93, respectively. While stack 83 is illustrated hereinfor purposes of disclosure as having a generally annular configuration,it is contemplated that various other stacks having differentconfigurations, such as a stack with at least one flat on itscircumferential surface or a stack defining an inside-out core of a typeknown to the art for instance, may be utilized within the scope of theinvention so as to meet at least some of the objects thereof.Furthermore, it is also contemplated that stack 83 may be formed of aplurality of individual laminations arranged in face-to-face relation ormay be helically wound from a continuous lamination strip within thescope of the invention so as to meet at least some of the objectsthereof. Whether stack 83 contains individual laminations or ishelically wound, it is also contemplated that the laminae of the stackmay be retained against displacement by suitable means well known to theart, such as for instance welding or cleating or the like, or that thestack may be of the loose laminae type well known in the art within thescope of the invention so as to meet at least some of the objectsthereof.

Upon the assembling of slot liner 31 with stack 83 in another method inone form of the invention, the slot liner may be generally aligned withslot 33 in the stack adjacent end face 85 thereof, as best seen in FIG.6, and the slot liner may be passed generally end-for-end into and inpart through the slot into its assembled position, as shown in FIGS.7-9. When slot liner 31 attains its assembled position in slot 33, itmay be noted that sheet 37 of the slot liner is interposed between theslot and sheet 39 of the slot liner, and opposite cuffs 69,69a on sheet39 are associated at least in part about the intersections of the slotwith opposite end faces 85,85a in resilient gripping engagement with theopposite end faces. Thus, opposite side portions 71,73 and end portion79 on sheet 37 of slot liner 31 are respectively engaged or seated atleast in part in confronting relation with opposed sidewalls 97,99 andend wall 101 of slot 33, and it may be further noted that apertures 41in sheet 37 not only communicate with non-apertured sections 47 in sheet39 but also with the opposed sidewalls and end wall of the slot.Furthermore it may also be noted that the preselected spacing S ismaintained between wall means 65,67 of respective adjacent ones ofapertures 41,43 in different adjacent sheets 37,39 of slot liner 31 whenthe slot liner is disposed in its assembled position with respect toslot 33 in stack 83, and apertures 43 in sheet 39 not only communicatewith non-apertured sections 45 in sheet 37 but also with the part of theslot defined within sheet 39. While the foregoing describes theplacement or injection of only one slot liner 31 in one slot 33 of stack83, it is contemplated that groups of the slot liners, or perhaps all ofthe slot liners, may be simultaneously inserted into the slots by theaforementioned shaping and injection apparatus (not shown) within thescope of the invention so as to meet at least some of the objectsthereof.

When slot liners 31 are disposed in their assembled positions in slots33 of stack 83, as discussed above, winding means 107 comprising aplurality of coils 109 of any suitably enameled, electrical conductivewire may be wound or otherwise placed or inserted into the slots, and itis contemplated that the winding means may be associated with the stackon any conventional coil winding and/or coil placement equipment (notshown) as is well known to the art. As may be best seen in FIGS. 8-10,upon the aforementioned association of winding means 107 with stack 83,a pair of opposite side turn portions 111,113 of coils 109 are receivedwithin sheets 39 of slot liners 31 arranged in their assembled positionswithin slots 33 of the stack thereby to electrically insulate thewinding means from the stack, and a pair of opposite end turn portions115,117 of the coils are arranged in generally annular groupings thereofabout bore 95 of the stack so as to be spaced adjacent opposite endfaces 85,85a of the stack, respectively. As illustrated schematically inFIG. 10, each coil 109 of winding means 107 includes at least one turnor loop of a conductor, such as the aforementioned enameled electricalconductive wire. Albeit not shown for purposes of drawing simplicity, itis contemplated that, if desired or if necessary, opposite end turnportions 115,117 of coils 109 may be shaped and/or pressed back into theaforementioned generally annular groupings thereof adjacent opposite endfaces 85,85a of stack 83 by suitable conventional equipment (not shown)which is well known to the art. As previously mentioned, the preselectedspaces S are maintained between apertures 41,43 in adjacent sheets 37,39of slot liners 31 when the slot liners are in their assembly positionsin slots 33, and such spacing S is provided to protect against voltagecreepage between winding means 107 and the wall means of the slots.

Either generally simultaneously with the association of winding means107 with stack 83 or subsequent thereto, a plurality of means, such asslot wedges 119 or the like for instance, may be placed or inserted atleast in part within slots 33 so as to extend at least across openings103 and between adjacent tooth tips 93 for maintaining opposite sideturn portions 111,113 against displacement from the slots through theopenings toward bore 95 of the stack, as best seen in FIGS. 8 and 9.While slot wedges 119 are shown herein as being arranged in part inoverlaying relation with opposite side portions 75,77 on sheet 39 ofslot liners 31 within slots 33, it is contemplated that the slot wedgesmay also be interposed in part between opposite side portions 71,73 onsheet 37 of the slot liner and opposed sidewalls 97,99 of the slots.Furthermore, albeit not shown, it is contemplated that a strip of phaseinsulating means may be provided in at least some of the slots 33 instack 83, if necessary or if desired to electrically insulate coils 109of different electrical phases. If a more complete discussion of theaforementioned phase insulating means is desired, reference may be hadto U.S. Pat. No. 4,485,126. As illustrated herein for purposes ofdisclosure, slot wedges 119 may be formed of any suitable dielectricmaterial, such as the aforementioned Mylar sheet material for instance;however, it is contemplated that other slot wedges having differentconfigurations and formed of different materials, such as for examplemagnetic slot wedges or the like, may be utilized within the scope ofthe invention so as to meet at least some of the objects thereof.

Subsequent to the association of winding means 107 with stack 83, core35 may be treated with a hardenable liquid adhesive material 121 by amethod in one form of the invention, as best seen in FIGS. 8, 11 and 12.For purposes of disclosure, liquid adhesive material 121 may be aformula I-800 water based varnish with a solid content in a range ofbetween generally about 9% and about 38%, and such liquid adhesivematerial is available from Schenectady Chemicals, Inc., Schenectady, NY;however, it is contemplated that various other liquid adhesivematerials, such as for instance solvent or water based varnishes,solventless resins or the like having either the same or different solidcontents than mentioned above, may be utilized within the scope of theinvention so as to meet at least some of the objects thereof.

In the practice of this core treating method, bore 95 in stack 83 ofcore 35 may be received or mounted for conjoint rotation on a rotatablemandrel 123 which is adapted to be rotated in preselected sequences bothclockwise and counterclockwise, as indicated by the opposite rotationalarrows in FIG. 11. Hardenable liquid adhesive material 121 may bedispensed at a preselected rate of flow from a plurality of protractiveand retractive nozzles 125,127 and 129,131 onto opposite end turnportions 115,117 of winding means 107 during the conjoint rotation ofthe core and mandrel, respectively. When so applied onto opposite endturn portions 115,117 of winding means 107, some liquid adhesivematerial 121 is retained in the interstices between the opposite endturn portions of coils 109, and the liquid adhesive material also flowsfrom the opposite end turn portions of the coils along opposite sideturn portions 111,113 of the coils into slots 33 in stack 83 within slotliners 31 and slot wedges 119 disposed generally in surrounding relationabout the opposite side turn portions of the coils received in theslots, as indicated by the liquid adhesive material flow arrows L inFIG. 8. If a more detailed explanation concerning the construction andoperation of apparatus for dispensing the liquid adhesive material ontothe core, the flow of the liquid adhesive material along the oppositeside and end turn portions of the coils into the slots, and variousalignment and/or mounting apparatus which may be associated with stack83 to insure axial alignment of slots 33, teeth 91 and bore 85 when thecore is associated with rotatable mandrel 123, reference may be had tothe aforementioned U.S. Pat. No. 4,559,698.

While some of the liquid adhesive material 121 introduced into slots 33of stack 83 within slot liners 31 disposed in the slots is retainedbetween the interstices of opposite side turn portions 111,113 of coils109 and also between the opposite side turn portions and sheets 39 ofthe slot liners in the slots, it may be noted that the liquid adhesivematerial is caused to flow through at least some of apertures 43 insheets 39, as indicated by the liquid adhesive material flow arrows L inFIG. 12. From apertures 43 in sheets 39 of slot liners 31, liquidadhesive material 121 is flowed or channeled by capillary action betweenat least some of the overlaying non-apertured sections 45,47 in sheets37,39 of the slot liners into at least some of apertures 41 in sheets 37which communicate directly with opposed sidewalls 97,99 and end walls101 of slots 33; therefore, it may also be noted that the liquidadhesive material is flowed from apertures 41 in sheets 37 by capillaryaction directly into communication between sheets 37 and the wall meansof the slots in stack 83, respectively. As previously mentioned, opposedsidewalls 97,99 and end walls 101 of slots 33 in stack 83 areintersected by interfacing lamination surfaces 105 of the stack, and itmay be further noted that some of the liquid adhesive material 121communicating between sheets 37 of slot liners 31 and the wall means ofslots 33 in stack 83 is effective to wet by capillary action at least apart of at least some of the interfacing lamination surfaces, as bestseen in FIG. 12.

It is believed that the positive and directed flow of liquid adhesivematerial 121 through apertures 41,43 in sheets 37,39 of slot liners 31into slots 33 of stack 83, as discussed above, effects a more uniformwetting of interfacing lamination surfaces 105 in the stack which isbelieved to result not only in a greater bond strength for core 35 uponthe curing of the liquid adhesive material but also in a more uniformbond strength from core to core utilizing the core treatment method ofthis invention. As previously mentioned, apertures 41,43 may beconcentrated or predeterminately spaced in their preselected patterns insheets 37,39 of slot liners 31 in order to predetermine the delivery ofliquid adhesive material to desired parts of opposed sidewalls 97,99 andend walls 101 of slots 33 in stack 83. In this manner, it may be notedthat liquid adhesive material 121 may be predeterminately directed towet interfacing lamination surfaces 105 intersecting with the opposedsidewalls 97,99 and end walls 101 at the aforementioned desired partsthereof in order to enhance the bond strength of core 35 upon the curingof the liquid adhesive material. It is also believed that theaforementioned positive, yet controlled, flow of liquid adhesivematerial 121 directed through apertures 41,43 in sheets 37,39 of slotliners 31, as discussed above, may be effected at a rate great enough toobviate undersirable passage of the liquid adhesive material from theslot liners onto opposite end faces 85,85a of stack 83 which, of course,would necessitate an additional operation and expense to clean or wipethe overflowed liquid adhesive material from the opposite end faces ofthe stack. It is also believed that circumferential surface 89 of stack83 is free of any liquid adhesive material 121 which wets by capillaryaction between interfacing lamination surfaces 105 which intersect withthe circumferential surface thereby to obviate an undesirable operationand expense of cleaning or wiping liquid adhesive material from thecircumferential surface of the stack. To complete the description of theabove discussed core treatment method as well as core 35, liquidadhesive material 121 may be cured or hardened by subjecting the core toheat and then cooling the core in any suitable manner well known to theart.

In FIGS. 13-18, an alternative slot liner or slot liner assembly 141 inone form of the invention and an alternative method of assembling slotliner 141 are illustrated, and the alternative slot liner and itsassembling method have generally the same structural and method featuresas the previously discussed slot liner 31 and its assembling method withthe exceptions noted below. Further, while alternative slot liner 141meets at least some of the objects of the invention set out hereinabove,it is believed that such alternative slot liner may have indigenousobjects and advantageous features as will be in part apparent and inpart pointed out hereinafter.

As best seen in FIGS. 13-15, slot liner 141 comprises a sheet 143 ofgenerally thin dielectric material, such as for instance theaforementioned Mylar sheet material or the like. Sheet 143 has a pair ofopposite surfaces 145,145a, and the opposite surfaces are interconnectedby a pair of sets of opposite marginal edges 147,147a and 149,149a withadjacent ones of the opposite marginal edges intersecting each other,respectively. As further discussed hereinafter, sheet 143 is providedwith a pair of imperforate parts or strips 151,151a extending alongopposite marginal edges 147,147a and between opposite surfaces 145,145a,and if desired, such imperforate strips may be delineated by fold lines153,153a impressed in the strip. Another generally central imperforatepart or strip 155 is provided in sheet 143 intermediate imperforatestrips 151,151a and extending generally parallel therewith betweenopposite surfaces 145,145a of the sheet. If desired, a plurality ofgenerally central and spaced apart fold lines 157,159,159a may beimpressed in sheet 143 in central imperforate strip 155 so as to extendbetween opposite marginal edges 149,149a and generally parallel withfold lines 153,153a. Albeit not shown for purposes of drawingsimplification and brevity of disclosure, it is contemplated thatadditional fold lines may be provided in sheet 143 within the scope ofthe invention so as to meet at least some of the objects thereof.

A plurality of apertures 161 are arranged in a preselected pattern insheet 143, and each aperture has wall means, such as a marginal wall ora sidewall 163 or the like for instance, defining its configuration withopposite ends or end portions of the wall means intersecting withopposite surfaces 145,145a of the sheet, respectively. Sheet 143 alsohas a plurality of non-apertured sections 165 which interconnect betweenapertures 161, respectively.

In practicing the aforementioned alternative assembling method, sheet143 is folded generally in half along central fold line 157 into a pairof overlaying layers 167,167a of the sheet, as best seen in FIGS. 14 and15. Thus, opposite surface 145a of sheet 143 is folded upon itself toalign opposite marginal edges 149,149a in overlaying layers 167,167a,respectively, and opposite marginal edges 147,147a are aligned adjacenteach other in the overlaying layers. In response to the folding of sheet143, imperforate strips 151,151a are disposed in overlaying relation inoverlaying layers 167,167a, and central imperforate strip 155 is foldedinto overlaying relation upon itself in the overlaying layers,respectively; therefore, fold lines 153,153a and 159,159a are generallyaligned in overlaying relation in the overlaying layers, respectively.Further, apertures 161 in each overlaying layer 167,167a are arranged innon-aligning or staggered relation with each other, and opposite surface145a on sheet 143 at non-apertured sections 165 is engaged about oneopposite end of aperture wall means 163, respectively. Thus, apertures161 in each layer 167,167a are communicated with non-apertured sections165 in an adjacent layer. As previously discussed, preselected space Sis provided between wall means 163 of adjacent apertures 161 indifferent adjacent layers 167,167a, respectively.

Upon the above discussed folding of sheet 143 and the establishment ofpreselected space S between apertures 161 in adjacent layers 167,167a,adjacent overlaid imperforate strips 151,151a and the overlaid centralstrip 155 may be further folded or deformed generally along the alignedfold lines 153,153a and 159,159a, respectively, thereby to form a pairof generally opposite cuffs 169,169a on the layers, and the oppositecuffs are angularly positioned in spaced overlaying relation with layer167, as best seen in FIGS. 14-16.

Subsequent to the formation of opposite cuffs 169,169a on layers167,167a, the layers and opposite cuffs may be conjointly deformed orshaped into a preselected configuration at least approximating theconfiguration of slot 33 in stack 83 thereby to define slot liner 141,as best seen in FIG. 16. When so shaped, layers 167,167a are deformedinto a generally U-shaped or horseshoe shaped configuration, and theaforementioned opposite marginal edges 149,149a respectively aligned inoverlaying relation in layers 167,167a are positioned generally inlaterally spaced relation with each other. Thus, layers 167,167a in theU-shaped configuration thereof define a pair of generally opposite sidesor side portions 171,171a and 173,173a with end or end portions 175,175aintegrally interconnected therebetween, respectively. Of course,opposite side portions 171,171a and 173,173a and end portions 175,175aextend between opposite cuffs 169,169a of layers 167,167a. To completethe description of slot liner 141 and its assembling method, it may benoted that the preselected space S between wall means 163 of adjacentapertures 161 in different layers 167,167a are maintained when thelayers are deformed into the generally U-shaped configuration thereof.

Of course, slot liner 141 may be placed or inserted into slot 33 ofstack 83 in the same manner as previously discussed with respect to slotliner 31. When so associated with slot 33 of stack 83, opposite cuffs169,169a are arranged in resilient gripping engagement with opposite endfaces 85,85a of the stack, and opposite side portions 171a,173a and endportion 175a in layer 167a are at least in part engaged or seated inconfronting relation with opposed sidewalls 97,99 and end wall 101 ofslot 33 in the stack, respectively, as best seen in FIG. 17. In thismanner, apertures 161 in layer 167a communicate with both the wall meansof slot 33 in stack 83 and non-apertured sections 165 in layer 167, andlayer 167 and slot wedges 119 are disposed generally in surroundingrelation about opposite side turn portions 111,113 in coils 109 ofwinding means 107 received in the slots of the stack. Thus, when liquidadhesive material 121 is applied onto winding means 107 so as to beintroduced into slots 33 of stack 83, as previously discussed, theliquid adhesive material flows through apertures 161 in layer 167, thenby capillary action between non-apertured sections 165 in layers167,167a, thereafter through apertures 161 in layer 167a, and bycapillary action between layer 167a and the wall means of the slots toeffect the wetting of interfacing lamination surfaces 105 intersectingwith the wall means of the slot, as best seen in FIG. 18.

In FIGS. 19-24, another alternative slot liner or slot liner assembly191 in one form of the invention and another alternative method ofasembling slot liner 191 are illustrated, and the alternative slot linerand its assembling method have generally the same structural and methodfeatures as the previously discussed slot liner 31 and its assemblingmethod with the exceptions noted below. Further, while alternative slotliner 191 meets at least some of the objects of the invention set outhereinabove, it is believed that such alternative slot liner may haveindigenous objects and advantageous features as will be in part apparentand in part pointed out hereinafter.

As best seen in FIGS. 19-21, slot liner 191 comprises a sheet 193 ofgenerally thin dielectric material, such as the aforementioned Mylarsheet material of the like for instance. Sheet 193 has a pair ofgenerally opposite surfaces 195,195a, and the opposite surfaces areinterconnected by a pair of sets of opposite marginal edges 197,197a and199,199a with the adjacent ones of the opposite marginal edgesintersecting each other, respectively. As further discussed hereinafter,sheet 193 is provided with a pair of imperforate parts or strips 201,201a laterally spaced from opposite marginal edges 197,197a andextending generally in parallel relation between opposite marginal edges199,199a, and if desired, such imperforate strips may be delineated byfold lines 203,205,205a and 207,209,209a impressed in the sheet,respectively. Another generally central imperforate part or strip 211,as indicated in dotted outline in FIG. 19, is provided in sheet 193extending generally in parallel relation with imperforate strips201,201a between opposite marginal edges 199,199a. Albeit not shown forpurposes of drawing simplification and brevity of disclosure, it iscontemplated that additional fold lines may be provided in sheet 193within the scope of the invention so as to meet at least some of theobjects thereof.

A plurality of apertures 213 are arranged in a preselected pattern insheet 193, and each aperture has wall means, such as a marginal wall ora sidewall 215 or the like for instance, defining its configuration withopposite ends or end portions of the wall means intersecting withopposite surfaces 195,195a of sheet 193, respectively. Sheet 193 alsohas a plurality of non-apertured sections 217 which interconnect betweenapertures 213.

In practicing the aforementioned assembling method, sheet 193 is foldedupon itself generally along fold lines 203,207 in imperforate strips201,201a into a pair of overlaying layers 219,219a of the sheet, as bestseen in FIGS. 20 and 21. In response to the folding of sheet 193,imperforate strips 201,201a are folded upon themselves generally at foldlines 203,207 so as to extend in both layers 219,219a, and oppositemarginal edges 197,197a are arranged generally in opposed relation atleast adjacent each other in layer 219 and in overlaying relation withcentral imperforate strip 211 in layer 219a, respectively. Further, foldlines 205,205a are generally aligned in overlaying relation with eachother in layers 219,219a, as are fold lines 209,209a, respectively. Itmay be noted that apertures 213 in each overlaying layer 219,219a arearranged in non-aligning or staggered relation with each other, andopposite surface 195 on sheet 193 at non-apertured sections 217 isengaged about one opposite end of aperture wall means 215, respectively.Thus, apertures 213 in each layer 219,219a are communicated withnon-apertured sections 217 in an adjacent layer. As previouslymentioned, preselected space S is provided between wall means 215 ofadjacent apertures 213 in different adjacent layers 219,219a,respectively.

Upon the above discussed folding of sheet 193 and the establishment ofpreselected space S between apertures 213, layers 219,219a may befurther folded or deformed at overlaying aligned fold lines 205,205a and209,209a in the layers thereby to form the overlaid imperforate strips201,201a into a pair of generally opposite cuffs 221,221a, and theopposite cuffs are generally angularly positioned in spaced overlayingrelation with layer 219, respectively, as best seen in FIGS. 20-22.

Subsequent to the formation of opposite cuffs 221,221a on layers219,219a, the layers and cuffs may be conjointly deformed or shaped intoa preselected configuration at least approximating the configuration ofslot 33 in stack 83 thereby to define or form slot liner 191, as bestseen in FIG. 22. When so shaped, layers 219,219a are deformed into ageneraly U-shaped or horseshoe shaped configuration, and theaforementioned opposite marginal edges 199,199a respectively aligned inoverlaying relations in layers 219,219a are positioned generally inlaterally spaced apart relation with each other. Thus, layers 219,219ain the U-shaped configuration thereof define a pair of generallyopposite sides or side portions 223,223a and 225,225a with end or endportions 227,227a integrally interconnected therebetween in layers219,219a, respectively. Of course, opposite side portions 223,223a and225,225a and end portions 227,227a extend between opposite cuffs221,221a on layers 219,219a. To complete the description of slot liner191 and its assembling method, it may be noted that preselected space Sbetween wall means 215 of adjacent apertures 213 in different adjacentlayers 219,219a are maintained when the layers are deformed into thegenerally U-shaped configuration thereof.

Slot liners 191 may be placed or inserted into slots 33 of stack 83 inthe same manner as previously discussed with respect to slot liner 31.When slot liners 191 are so associated with slots 33, opposite cuffs221,221a are arranged in resilient gripping engagement with opposite endfaces 85,85a of stack 83, and opposite side portions 223,223a and endportion 227 in layer 219 are at least in part engaged or seated inconfronting relation with opposed sidewalls 97,99 and end wall 101 ofslot 33 in the stack, as best seen in FIG. 22. In this manner, apertures213 in layer 219 communicate with both the wall means of slots 33 instack 83 and non-apertured sections 217 in layer 219a, and layer 219aand slot wedge 199 are overlapped so as to be disposed generally insurrounding relation about opposite side turns portions 111,113 of coils109 received in the slots of the stack, respectively. Thus, when liquidadhesive material 121 is applied onto winding means 107 so as to beintroduced into slots 33 of stack 83, as previously discussed, theliquid adhesive material flows through apertures 213 in layer 219a, thenby capillary action between the non-apertured sections 217 in layers219,219a, thereafter through apertures 213 in layer 219, and bycapillary action between the wall means of the slots to effect thewetting of interfacing lamination surfaces 105 intersecting with thewall means of the slots, as best seen in FIG. 24.

Although cuffs 169,169a of slot liner 141 and cuffs 221,221a of slotliner 191 are illustrated herein as being imperforate for purposes ofdisclosure, it is contemplated that apertures 161,213 may be provided incuffs 169,169a and 221,221a with the provision that the preselectedspaces S are maintained between the apertures in the different adjacentlayers of the cuffs, respectively, within the scope of the invention soas to meet at least some of the objects thereof.

From the foregoing, it is apparent that novel slot liners 31,141,191and, a novel core 35 have been presented meeting the objects set outhereinbefore, as well as others, and it is contemplated that changes asto the precise arrangement, details and connections of the componentsutilized in such slot liners and core may be made by those havingordinary skill in the art without departing from the spirit of theinvention or the scope of the claims which follow.

What we claim as new and desire to obtain by U.S. Letters Patent is: 1.A core for a dynamoelectric machine comprising:a pair of generallyopposite end faces on the core; a circumferential yoke between saidopposite end faces; at least a pair of adjacent teeth extending onpreselected pitch axes from said yoke and between said opposite endfaces, respectively, and each adjacent tooth including a tip end spacedfrom said yoke; at least one winding receiving slot in the core disposedbetween said yoke and said adjacent teeth and intersecting with saidopposite end faces, said at least one slot including a pair of generallyopposed sidewalls on said adjacent teeth, an end wall on said yokeinterposed between said opposed sidewalls, and an opening extendingbetween said tip ends of said adjacent teeth and said opposite end facesand arranged generally opposite said end wall; a first sheet ofgenerally thin dielectric material disposed at least in part within saidat least one slot and including a pair of first opposite side portionsdisposed in confronting relation at least adjacent said opposedsidewalls, a first end portion interposed between said first oppositeside portions and disposed in confronting relation at least adjacentsaid end wall, a plurality of first apertures in said first end andopposite side portions, said first apertures having a pair of oppositeends with at least some of one of said first opposite ends beingdisposed at least adjacent said end wall and opposite sidewalls, and aplurality of first non-apertured sections in said first end and oppositeside portions and interconnected between said first apertures,respectively; a second sheet of generally thin dielectric materialdisposed at least in part within said at least one slot in overlayingrelation with said first sheet, said second sheet including a pair ofsecond opposite side portions disposed in confronting relation at leastadjacent said first opposite side portions, a second end portioninterposed between said second opposite side portions and disposed inconfronting relation at least adjacent said first end portion, aplurality of second apertures in said second end and opposite sideportions and arranged in non-aligned relation with said first apertures,said second apertures having a pair of second opposite ends with atleast some of one of said second opposite ends being disposed inoverlaying relation at least adjacent at least some of said firstnon-apertured sections, a plurality of second non-apertured sections insaid second end and opposite side portions and interconnected betweensaid second apertures, at least some of said second non-aperturedsections being disposed in overlaying relation at least adjacent atleast some of the other of said first opposite ends, and a pair ofgenerally opposite cuffs on said second end and opposite side portionsand disposed at least adjacent said opposite end faces generally at theintersections of said at least one slot with said opposite end faces,respectively.
 2. A core for a dynamoelectric machine comprising:agenerally axial stack of ferromagnetic material including a pair ofgenerally opposite end faces, and wall means in said stack for definingat least one winding receiving slot intersecting with said opposite endfaces, respectively; a first sheet of generally thin dielectric materialdisposed at least in part within said at least one winding receivingslot in confronting relation at least adjacent said wall means, saidfirst sheet including a plurality of first apertures arranged in apreselected pattern in said first sheet, and a plurality of firstnon-apertured sections connecting between said first apertures,respectively; and a second sheet of generally thin dielectric materialdisposed at least in part in overlaying relation with said first sheetand at least in part within said at least one winding receiving slot,said second sheet including a plurality of second apertures arranged ina preselected pattern in said second sheet and predeterminatelymisaligned with said first apertures, at least some of said secondapertures being communicated with at least some of said firstnon-apertured sections, and a plurality of second non-apertured sectionsconnected between said second apertures, at least some of said firstapertures being communicated with both said wall means and at least someof said second non-apertured sections, respectively.
 3. The core as setforth in claim 2 wherein said second sheet further includes a pair ofgenerally opposite cuffs disposed in confronting relation at leastadjacent said opposite end faces generally at the intersections of saidat least one slot with said opposite end faces, respectively.
 4. Thecore as set forth in claim 3 wherein said second sheet further includesat least one pair of generally opposite marginal edges, and a pair ofimperforate strips in said second sheet adjacent said at least one pairof opposite marginal edges and defining said opposite cuffs,respectively.
 5. The core as set forth in claim 3 wherein said firstsheet further includes at least one pair of generally opposite marginaledges disposed at least adjacent said opposite cuffs, respectively. 6.The core as set forth in claim 2 wherein said first and second apertureseach include a marginal wall defining the configuration thereof witheach marginal wall in one of said first and second sheets beingpredeterminately spaced from others of said marginal walls in the otherof said first and second sheets arranged adjacent said each marginalwall.
 7. The core as set forth in claim 6 wherein the spacing betweensaid each marginal wall and said other marginal walls is not less thanabout 0.094 inches (2.49 mm).
 8. The core as set forth in claim 2further comprising a winding including a plurality of coils, each coilhaving at least one conductor turn with a pair of generally oppositeside turn portions interposed between a pair of generally opposite endturn portions, one of said opposite side turn portions of some of saidcoils extending through said at least one winding receiving slotadjacent said second sheet and the opposite end turn portions of saidcoils being arranged in generally annular groupsing thereof adjacentsaid opposite end faces of said strack, respectively.
 9. The core as setforth in claim 8 further comprising a hardenable liquid adhesivematerial hardened in place in at least parts of said winding and saidstack at least within said at least one winding receiving slot therebyto bond said stack, said windings and at least said first and secondsheets into a generally unitary mass.
 10. A core for a dynamoelectricmachine comprising:a pair of generally opposite end faces on the core;wall means in the core for defining at least one winding receiving slotintersecting with said opposite end faces, respectively; and a pluralityof layers of generally thin dielectric material associated at least inpart in overlaying relation and disposed at least in part within said atleast one slot, each layer including a set of apertures arranged in apreselected pattern and with said apertures in adjacent layers beingdisposed in non-aligning relation, and a set of non-apertured sectionsbetween said apertures, at least some of said apertures in each layerbeing communicated with at least some of said non-apertured sections inan adjacent layer and said at least some apertures in one of said layersalso being communicated with said wall means, respectively.
 11. The coreas set forth in claim 10 wherein each aperture includes a marginal walldefining its configuration with a spacing between adjacent marginalwalls in different adjacent layers being at least about 0.094 inches(2.39 mm), respectively.
 12. The core as set forth in claim 10 whereinanother of said layers disposed in the overlaying relation with said onelayer includes a pair of generally opposite cuffs arranged inconfronting relation at least adjacent said opposite end faces generallyat the intersections of said at least one slot with said opposite endfaces, respectively.
 13. The core as set forth in claim 10 wherein saidlayers further include a pair of folded parts defining a pair ofgenerally opposite cuffs disposed in confronting relation at leastadjacent said opposite end faces generally at the intersections of saidat least one slot with said opposite end faces, respectively.
 14. Thecore as set forth in claim 13 wherein said one layer includes a pair ofmarginal edges arranged generally in opposed relation between saidfolded parts, and another of said layers adjacent said one layerincluding an imperforate strip arranged in overlaying relation acrosssaid marginal edges.
 15. The core as set forth in claim 10 wherein saidlayers further include a folded part defining a cuff, a pair of adjacentmarginal edges, another folded part generally adjacent said adjacentmarginal edges and defining another cuff spaced generally opposite saidfirst named cuff, and said first named and another cuffs being disposedin confronting relation at least adjacent said opposite end facesgenerally adjacent the intersections of said at least one slot with saidopposite end faces, respectively.
 16. The core as set forth in claim 10further comprising winding means for association with the core, saidwinding means including a plurality of coils, each coil having at leastone conductor turn defining a pair of generally opposite side turnportions interposed between a pair of generally opposite end turnportions, said opposite end turn portion being arranged in generallyannular groupings thereof respectively adjacent said opposite end facesof said stack and said opposite side turn portions extending across saidstack with one of said opposite side turn portions of some of said coilsbeing disposed within said at least one slot adjacent another of saidlayers.
 17. The core as set forth in claim 10 further comprising awinding means for association with the core, a hardenable liquidadhesive material hardened in place in at least parts of said windingmeans and the core thereby to bond said winding means, the core and saidlayers into a generally unitary mass.
 18. The core as set forth in claim17 further comprising a generally axial stack of ferromagnetic materialhaving at least a generally annular yoke section, said at least one slotextending across said axial stack at least in part adjacent said yokesection, a plurality of interfacing surfaces defined by saidferromagnetic material within said axial stack and intersecting with atleast said least one slot, said hardened hardenable liquid adhesivematerial being disposed in bonding relation between at least parts of atleast some of said interfacing surfaces.
 19. A slot liner for a windingreceiving slot in a core for a dynamoelectric machine, the slot linercomprising:a first sheet of generally thin dielectric material includinga pair of firs generally opposite side portions, a first end portioninterposed between said first opposite side portions, a plurality offirst apertures arranged in a preselected pattern and extending throughsaid first end and opposite sides portions, said first apertures havinga plurality of first marginal walls defining the configuration of saidfirst apertures, and a pair of generally opposite cuffs extending fromat least a part of said first end and opposite side portion,respectively; and a second sheet of generally thin dielectric materialdisposed in overlaying relation with said first sheet between saidopposite cuffs, said second sheet including a pair of second generallyopposite side portions disposed in confronting relation at leastadjacent said first opposite side portions, a second end portioninterposed between said second opposite side portions and disposed inconfronting relation at least adjacent said first end portion, aplurality of second apertures arranged in a preselected pattern andextending through said second end and opposite side portions, saidsecond apertures having a plurality of second marginal walls definingthe configuration of said second apertures, said first and secondapertures being disposed in non-aligning relation with each of saidfirst and second marginal walls being spaced at least about 0.094 inches(2.39 mm) from each other, and a plurality of second non-aperturedsections in said second end and opposite side portions, at least some ofsaid second apertures being communicated with at least some of saidfirst non-aperture sections and at least some of said first aperturesbeing communicated with at least some of said second non-aperturedsections, respectively.
 20. A slot liner for a winding receiving slot ina core of a dynamoelectric machine, the slot liner comprising:a firstsheet of generally thin dielectric material including a plurality offirst apertures arranged in a preselected pattern and extending throughsaid first sheet, a plurality of first non-apertured sectionsinterconnecting with said first apertures, and a pair of generallyopposite cuffs on said first sheet, respectively; a second sheet ofgenerally thin dielectric material disposed at least in part inoverlaying relation with said first sheet and extending generallybetween said opposite cuffs, said second sheet including a plurality ofsecond apertures arranged in a preselected pattern and extending throughsaid second sheet, said second apertures being arranged in non-alignedrelation with said first apertures, and a plurality of secondnon-apertured sections interconnecting with said second apertures, atleast some of said second apertures being communicated with at leastsome of said first non-apertured sections and at least some of saidfirst apertures being communicated with at least some of said secondnon-apertured sections, respectively.
 21. The slot liner as set forth inclaim 20 wherein each first and second aperture includes a marginal walldefining its configuration, and each marginal wall of said first andsecond apertures being predeterminately spaced from each other,respectively.
 22. The slot liner as set forth in claim 21 wherein thepredetermined space between said marginal wall each of said first andsecond apertures is at least about 0.094 inches (2.39 mm).
 23. A slotliner assembly for a winding receiving slot in a core of adynamoelectric machine, the slot liner comprising:a plurality of layersof generally thin dielectric material associated at least in part inoverlaying relation, each layer including a plurality of aperturesextending therethrough and arranged in a preselected pattern, and apluarilty of non-apertured sections between said apertures, saidapertures in adjacent layers being disposed in non-aligning relation andat least some of the apertures in each layer being disposed incommunication with at least some of the non-apertured sections in anadjacent layer, respectively.
 24. The slot liner as set forth in claim23 wherein each aperture includes wall means for defining itsconfiguration, and each wall means in each layer being spaced fromadjacent wall means in said adjacent layers at least about 0.094 inches(2.39 mm).
 25. The slot liner as set forth in claim 23 wherein one ofsaid layers includes a pair of generally opposite cuffs and another ofsaid layers extends between said opposite cuffs.
 26. The slot liner asset forth in claim 23 wherein said layers includes a folded partdefining a cuff, a pair of overlaid adjacent marginal edges, and anotherfolded part adjacent said overlaid adjacent marginal edges and defininganother cuff generally opposite said first named cuff.
 27. The slotliner assembly as set forth in claim 23 wherein said layers furtherinclude a pair of generally opposite folded parts defining a pair ofgenerally opposite cuffs on said layers, respectively.
 28. The slotliner assembly as set forth in claim 27 wherein one of said layersincludes a pair of marginal edges arranged generally in opposed relationbetween said folded parts, and another of said layers includes animperforate strip arranged in overlaying relation across said marginaledges.